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<TITLE>Simple plug-in example</TITLE>

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<H1>
Plug it in: Hello World meets the workbench</H1>
<P >
The Eclipse platform is structured as a core runtime engine and a set of additional features that are installed as platform
<b>plug-ins</b>. Plug-ins contribute functionality to the platform by contributing to pre-defined
<b> extension points</b>. The workbench UI is contributed by one such plug-in. When you start up the workbench, you are not starting up a single Java program. You are activating a platform runtime which can dynamically discover registered plug-ins and start them as needed.</P>
<P >
When you want to provide code that extends the platform, you do this by defining
system extensions in your plug-in. The platform has a well-defined set of extension
points - places where you can hook into the platform and contribute system behavior. From the platform's perspective, your plug-in is no different
than basic plug-ins like the resource management system or the workbench itself.</P>
<P >
So how does your code become a plug-in?&nbsp;</P>
<ul>
  <li>Decide how your plug-in will be integrated with the platform.</li>
  <li>Identify the extension points that you need to contribute in order to
    integrate your plug-in.</li>
  <li>Implement these extensions according to the specification for the
    extension points.</li>
  <li>Provide a manifest file (manifest.mf) that describes the packaging and
  prerequisites for your code, and a plug-in manifest (plugin.xml) that
  describes the extensions you are defining.</li>
</ul>
<P >
The process for creating a plug-in is best demonstrated by implementing an old classic, 
&quot;Hello World,&quot; as a plug-in.  The intention of this example is to give you a flavor
of how plug-in development is different from Java application development.  We'll gloss over a 
lot of details in order to get the plug-in built and running.  Then we'll look at extension
points in more detail, see where they are defined, and learn how plug-ins describe their implementation of an extension.</P>

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